WordPress Cache Refactoring Example

CacheDataInterface.php

<?php

interface CacheDataInterface {
	public function setIndex($name, $group = '');
	public function index();
	
	public function setData( $value );
	public function data();
	
	public function increment( $offset = 1 );
	public function decrement( $offset = 1 );
	
	public function setExpiration( $time = 0 );
	public function expiration();
	
	public function setForce( $force = false );
	public function force();
	
	public function toArray();
	public function fromArray( array $data );
}

CacheStorageInterface.php

<?php

interface CacheStorageInterface {
	public function initialize();
	
	public function deinitialize();
	
	public function add( CacheDataInterface $cache );
	
	public function remove( CacheDataInterface $cache );
	
	public function get( CacheDataInterface $cache, &$found = null );
	
	public function set( CacheDataInterface $cache );
	
	public function replace( CacheDataInterface $cache );
	
	public function flush();
	
	public function reset();
}

registry.php

<?php

function cache_registry(CacheStorageInterface $storage = null) {
	static $_storage = null;
	
	if ( is_object($storage) ) {
		$_storage = $storage;
	}
	
	if ( !is_object($_storage) ) {
		$_storage = new Default_Cache_Storage;
	}
	
	return $_storage;
}

function cache_data_object_name( $className = null ) {
	static $_objectName = 'Default_Cache_Object';
	
	if ( $className !== null && class_exists($className) ) {
		$_objectName = $className;
	}
	
	return $_objectName;
}

function cache_new_data_object() {
	$objName = cache_data_object_name();
	return new $objName;
}

function cache_set_data_object( $key, $data, $group = '', $expire = 0 ) {
	return cache_new_data_object()->setIndex( $key, $group )->setExpire( (int) $expire )->setData($data);
}

wp-cache.php

<?php

function wp_cache_add( $key, $data, $group = '', $expire = 0 ) {
	return cache_registry()->add( cache_set_data_object( $key, $data, $group, $expire ) );
}

function wp_cache_delete($key, $group = '') {
	return cache_registry()->remove( cache_new_data_object()->setIndex( $key, $group ) );
}

function wp_cache_get( $key, $group = '', $force = false, &$found = null ) {
	$cache = cache_new_data_object()->setIndex( $key, $group )->setForce( $force );
	return cache_registry()->get( $cache, &$found )->data();
}

function wp_cache_incr( $key, $offset = 1, $group = '' ) {
	$cache = cache_registry()->get( cache_new_data_object()->setIndex( $key, $group ) );
	return cache_registry()->replace( $cache->increment( $offset ) );
}

function wp_cache_decr( $key, $offset = 1, $group = '' ) {
	$cache = cache_registry()->get( cache_new_data_object()->setIndex( $key, $group ) );
	return cache_registry()->replace( $cache->decrement( $offset ) );
}

function wp_cache_replace( $key, $data, $group = '', $expire = 0 ) {
	return cache_registry()->replace( cache_set_data_object( $key, $data, $group, $expire ) );
}

function wp_cache_set( $key, $data, $group = '', $expire = 0 ) {
	return cache_registry()->set( cache_set_data_object( $key, $data, $group, $expire ) );
}

function wp_cache_switch_to_blog( $blog_id ) {
	$obj = cache_registry();
	if ( method_exists($obj, 'switch_to_blog') ) {
		return $obj->switch_to_blog( $blog_id );
	}
	if ( method_exists($obj, 'wp_cache_switch_to_blog') ) {
		return $obj->wp_cache_switch_to_blog( $blog_id );
	}
	return null;
}

function wp_cache_add_global_groups( $groups ) {
	$obj = cache_registry();
	if ( method_exists($obj, 'add_global_groups') ) {
		return $obj->add_global_groups( $groups );
	}
	if ( method_exists($obj, 'wp_cache_add_global_groups') ) {
		return $obj->wp_cache_add_global_groups( $groups );
	}
	return null;
}

function wp_cache_add_non_persistent_groups( $groups ) {
	$obj = cache_registry();
	if ( method_exists($obj, 'add_non_persistent_groups') ) {
		return $obj->add_non_persistent_groups( $groups );
	}
	if ( method_exists($obj, 'wp_cache_add_non_persistent_groups') ) {
		return $obj->wp_cache_add_non_persistent_groups( $groups );
	}
	return null;
}

function wp_cache_flush() {
	return cache_registry()->flush();
}

function wp_cache_init() {
	return cache_registry()->initialize();
}

function wp_cache_close() {
	return cache_registry()->deinitialize();
}

function wp_cache_reset() {
	_deprecated_function( __FUNCTION__, '3.5' );
	return cache_registry()->reset();
}